Sea Technology

DEC 2018

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

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Page 26 of 52

26 ST | December 2018 sel operating conditions. The AkzoNobel fouling control marine biology, hydrodynamics and coatings research teams are incorporating investigatory methods from across the multidisciplinary fields of biofilm science to better understand the diverse properties of biofilms that form on marine surfaces, whether or not coated, and, in parallel, improve our coating development processes. Diversity of Biofilms In Marine Industry If you survey the hulls of newly drydocked ships around the world, or even the experimental coating panels that have been immersed at our field test- ing sites, you would intuitively grasp that not all fouling biofilms are the same. They vary in color, texture, spatial coverage and thickness, and these visual cues suggest there might be further differ- ences in slime microbial communities and in the frictional drag penalties attached to these different biofilms. So, our fouling control R&D teams have been asking whether we could develop a biologi- cal slime metric that was a robust predictor of the associated drag penalty. Diatoms. For the biologists in the team, a natural first approach has been to look at the communities in fouling biofilms. Marine ship biofilms generally comprise both bacterial and microalgal popula- tions, and one of the most recognizable constitu- ent microbial groups are the diatoms. These single microalgal cells are encased in intricate silica shells and can be identified by shell morphology. We've used both environmental scanning electron microscopy and stan- dard light microscopy on biofilm samples collected from ships and cataloged the slime diatom diversity at differ- ent hull locations, demonstrating that ship slime varies along and down the hull and varies from ship to ship and from coating to coating. Pigments. Though diatoms are common in fouling marine biofilms, they are by no means the only microal- gae present. All the microalgae contain pigments that they use to convert light to energy by photosynthesis and An example of multispectral imaging approach to mapping biofilm density, which has roots in satellite sensing of global vegetation and ocean productivity.

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